- Aug 15, 2020
I'm fairly sure they are the same series of Garrett turbo; I believe 28s, or maybe 31s, although those come with a choice of slightly bigger or smaller compressors and he may have juggled that a bit. But it's pretty much the same compressor map. The turbines will be the same size in the same series.Peter has a smaller turbo as the LP!
If you can find some footage of his engine you will see that the hose going from the compressor discharge on that first turbo [HP unit sitting on exhaust manifold] is necked down ridiculously in order to adapt to the much bigger compressor mouth on that aft turbo; the thing looks like a toilet plunger.
You will notice the hot rodders, as in that video I linked to, select turbos where the outlet and corresponding inlet sizes are the SAME diameter. So the first compressor outlet size will match the mouth diameter on the second compressor. This also means that the hot side match will be similar. Since turbos are designed to flow at a particular air flow velocity, matching those sizes is a good clue that they are properly sized.
There is more to designing a staged setup than that of course, but this is a pretty idiot-proof first step. Having so obviously failed that step does not inspire confidence as to what other surprises may be lurking elsewhere in this 'airplane'.